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  1. #21  
    Quote Originally Posted by creighton
    FWIW, if you wanted to add 8% to some number, the math would NOT be 10 + 8 x .01 as suggested by westronic. It would either be 10 + 8 * 0.1 OR 10 + 80 * 0.01. As long as we trying to be accurate...
    Actually, as long as we trying to be accurate, NEITHER 10 + 8 * 0.1 nor 10 + 80 * 0.01 will and 8% to some number. Try it with, say , 20. Now we all know that the correct result of adding 8% of 20 to 20 would be 21.6. 20+8*.1 = 20.8, 20 + 80*.01 = 20.08, wrong in both cases.

    20 X 1.08 = 21.6, as does 20 X 8 % + 20.
  2. Me2
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    #22  
    Quote Originally Posted by tundycentral
    OK OK stop it! There is no damned debate here guys! Any other standard calculator on the planet worth it's salt will give you this: 10 + 8% = 10.8 (or 10.80 depending on where you have the decimal set).

    The calculator is screwed... just deal with it.
    You mean any calculator on the planet that does it _your_ way gives you 10.8. That doesn't make it right

    Westronic has it spot on. The expression "10 + 8%" does not define any order of operation. According to convention, in the absence of any parentheses to define this order, you should apply the PEMDAS principle [ Parentheses / Exponents / Multiplication & Division / Addition & Subtraction ].

    "Per Cent" simply means "divide by 100".

    So Please Excuse My Dear Aunt Sally would say that "10 + 8%" should be worked out as:
    Multiplication/Division first: 8/100 = .08
    followed by Addition/Subtraction: 10 + .08 = 10.08

    But the majority of off-the-shelf calculators are designed with commerce, accountancy and shopping in mind, so have been modified to interpret the "10 + 8%" instruction as a markup instead of the true form: 10 + (10*(8/100)) = 10.8

    The Treo "Basic" calculator is basic by nature - it simply emulates a mechanical "adding machine", which can only operate in single steps so has to do a subtotal after each entry:-
    10+8 = 18
    /100 = 0.18
    Last edited by Me2; 03/12/2005 at 11:48 AM.
  3. #23  
    Thanks to this thread, I learned that what I thought was a useless calculator has an advanced mode and is actually a most excellent calculator that does more than my venerable HP 15c! (except RPN, but that's okay).

    The Treo 650 calculator seems completely accurate, given that the % key is mathematically ambiguous and best avoided.

    P.S. I assert that 10 + 8% = 10.08.
    Palm user since 1999-04-16: III > IIIx > Vx > Sony N610c > SJ33 > Treo 650 GSM > Centro CDMA
  4. #24  
    Quote Originally Posted by Jeff DLB
    Thanks to this thread, I learned that what I thought was a useless calculator has an advanced mode and is actually a most excellent calculator that does more than my venerable HP 15c! (except RPN, but that's okay).

    The Treo 650 calculator seems completely accurate, given that the % key is mathematically ambiguous and best avoided.

    P.S. I assert that 10 + 8% = 10.08.
    And I learned that some people refuse to admit that the 650 is imperfect in any way, even something as simple and provable as an equation that is performed differently on every other calculator used. Sad.
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    #25  
    Quote Originally Posted by geatches
    And I learned that some people refuse to admit that the 650 is imperfect in any way
    Sorry - go to any elementary math class with 10 + 8% and you will be turned away without an answer. The statement follows none of the standard MATHEMATICAL conventions, despite the fact a calculator may give you an answer.

    It's the same ambiguity that results when you use the rule "5 or more round up". I like to play this game with elementary age kids - 1.5 rounds to 2, but so does 1.445. Clearly, 1.445 is NOT closer to 2 than to 1. You cannot call something a rule just because a lot of people do it. If you use imprecise language, you are bound to get different results from different "interpreters" - in this case the calculator. Personally, if you did the calculation conversationally what is ten plus eight.... percent, the value 0.18 is as good an answer as any.

    Some people just need to describe every "issue" as a "problem"....
  6. #26  
    Calculator? Here's one that I use. Of course, it's one I wrote so I'm kind of partial to it.

    (2 meg AVI file)
  7. #27  
    This issue has been discussed before...
    .
    .....
    MarkEagle
    .....<a href="http://discussion.treocentral.com/tcforum/index.php?s=">TreoCentral</a> | <a href="http://discussion.visorcentral.com/vcforum/index.php?s=">VisorCentral</a> Forum Moderator - Forum Guidelines
    .....Sprint PCS Treo 650
    .....God bless America, my home sweet home...
  8. #28  
    Quote Originally Posted by pabo
    Sorry - go to any elementary math class with 10 + 8% and you will be turned away without an answer. The statement follows none of the standard MATHEMATICAL conventions, despite the fact a calculator may give you an answer.

    It's the same ambiguity that results when you use the rule "5 or more round up". I like to play this game with elementary age kids - 1.5 rounds to 2, but so does 1.445. Clearly, 1.445 is NOT closer to 2 than to 1. You cannot call something a rule just because a lot of people do it. If you use imprecise language, you are bound to get different results from different "interpreters" - in this case the calculator. Personally, if you did the calculation conversationally what is ten plus eight.... percent, the value 0.18 is as good an answer as any.

    Some people just need to describe every "issue" as a "problem"....
    Then why does every other calculator give a different result? Oh, I forgot, this must be another case of "user error".

    apologist

    n : a person who argues to defend or justify some policy or institution
  9. #29  
    Quote Originally Posted by Silver5
    I entered the following:....

    It gets worse. I switched to the advanced mode and did the calculation on the 650 and got 10.64.

    So, I suggest that those of you who use your calculators look into something other than what comes bundled, because I sure as hell wouldn't trust it.
    how did you press the "%" key in advanced mode ? I take it you mean in Advanced Finance ?

    BTW I have a maths degree and belive me 10 + 8% in maths.... is incorrect..and has been said before its pot luck on what answer comes from what device..

    % is not an operator its a modifier there fore

    10+8% = (10+8)% = 18 / 100 = 10.8
  10. #30  
    Quote Originally Posted by Nobackup
    18 / 100 = 10.8
    Ummm... doesn't this equal .18?
    .
    .....
    MarkEagle
    .....<a href="http://discussion.treocentral.com/tcforum/index.php?s=">TreoCentral</a> | <a href="http://discussion.visorcentral.com/vcforum/index.php?s=">VisorCentral</a> Forum Moderator - Forum Guidelines
    .....Sprint PCS Treo 650
    .....God bless America, my home sweet home...
  11. #31  
    Quote Originally Posted by geatches
    And I learned that some people refuse to admit that the 650 is imperfect in any way, even something as simple and provable as an equation that is performed differently on every other calculator used. Sad.
    Oh, for goodness sakes.

    I am not saying the 650 is perfect, by any means.

    This particular calculation is performed EXACTLY as it would be on ANY simple mechanical calculator. It is in the "BASIC" mode, after all.

    The reason it gives a different result than many others is because they are set up with different rules for this INCORRECT series of keystrokes.

    The calculator itself works just fine once you understand how it is working and enter your formulas correctly.

    As for the "advanced" mode - there is no percent key there, so you can't do this is "advanced" mode.

    It is certainly NOT the calculator's fault if you enter what amounts to a nonsense series of keystrokes and don't get the answer you expect.
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    #32  
    Quote Originally Posted by geatches
    apologist

    n : a person who argues to defend or justify some policy or institution

    Knucklehead

    n: someone who takes something as fact just because everyone else believes it is so....

    A quick google will show that a majoriy of websites state the earth is flat and we never landed on the moon....

    ...must be true
  13. pabo's Avatar
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    #33  
    Quote Originally Posted by geatches
    ...on every other calculator used. Sad.
    where do you keep all those calculators ? ...must have a big garage...
  14. #34  
    Quote Originally Posted by westronic
    As for the "advanced" mode - there is no percent key there, so you can't do this is "advanced" mode.
    Advanced Mode - Finance does have a percent key.
    .
    .....
    MarkEagle
    .....<a href="http://discussion.treocentral.com/tcforum/index.php?s=">TreoCentral</a> | <a href="http://discussion.visorcentral.com/vcforum/index.php?s=">VisorCentral</a> Forum Moderator - Forum Guidelines
    .....Sprint PCS Treo 650
    .....God bless America, my home sweet home...
  15. #35  
    Quote Originally Posted by pabo
    where do you keep all those calculators ? ...must have a big garage...
    at your mother's house.
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    #36  
    Quote Originally Posted by geatches
    at your mother's house.
    not just stupid, but ignorant, too.
  17. #37  
    Quote Originally Posted by pabo
    not just stupid, but ignorant, too.
    No need to get offended Oedipus, it was a joke.
  18. #38  
    Quote Originally Posted by MarkEagle
    Advanced Mode - Finance does have a percent key.
    Yes, but shouldn't you have explained to him how it works?

    10 + 8 % 10 = 10.80

    100 + 25 % 4 = 101

    Thinking he'll hate it...
    Last edited by barky81; 03/12/2005 at 06:54 PM. Reason: typo
  19. pabo's Avatar
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    #39  
    Quote Originally Posted by geatches
    Oedipus
    wow, you actually are smart.

    offense taken.
  20. #40  
    Quote Originally Posted by pabo
    wow, you actually are smart.

    offense taken.
    You'll get over it.
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